Tube cutting tools are well known in the art and typically comprise a cutting wheel rotatably mounted on a pivotable arm or a movable jaw of the tool such that it may be biased into contact with the outer surface of the tube. Means are provided to draw the cutting wheel around the outer periphery of the tube, causing the cutter wheel to score the surface. As a complete revolution about the tube is completed, the cutting wheel is further biased against the tube's surface until the tube wall is cut completely through.
In its most rudimentary form, such cutting tools have a cutting head to which the cutting wheel arm or jaw is attached and some form of handle such that the entire cutting head may be rotated about the tube. In order to minimize the sliding friction between the cutter head and the tube, one or more support rollers may be incorporated into the cutter head to act as roller bearings as the head is drawn around the tube.
In those instances where the tube is readily accessible, the known tube cutters have proven satisfactory. However, it is often necessary to cut a tube which has limited accessibility. In modern aircraft, machinery and other structures where space is at a premium, it is often necessary to run tubing through very limited access areas. This presents a significant problem when it becomes necessary to remove or replace parts and the tubing must first be severed. Quite obviously, such situations prevent the use of the aforementioned tube cutting tools in which the entire tool must be rotated about the tube.
Tube cutting tools have been proposed which utilize a ratchet mechanism interposed between a cutter head and an actuating handle such that the handle itself need not be passed completely around the tube. The cutting head is rotated by oscillating the handle back and forth until the cutter head passes around the tube a sufficient number of times to sever the tube wall. While these devices have somewhat alleviated the problem of cutting tubes having limited accessibility, their jaw or arm feeding mechanisms have rendered them more bulky than necessary and, consequently, have limited their applicability to tubes having extremely tight clearances. Furthermore, these devices are limited strictly to manual operation and are incompatible with any power drive mechanism.
It is also known to provide such cutting tools having rotatable cutting heads with a power drive mechanism. Such mechanisms typically utilize a gear formed on the exterior surface of the rotatable cutting head which meshes with a pair of worm drive gears. The worm drive gears may, in turn, be driven by bevel gears in operative contact with a power source. While such tube cutters have alleviated the problems associated with the manually operated cutting tools, the use of worm drive gears has unnecessarily enlarged the size of the cutting tool such that it may not be utilized to cut tubing having extremely tight clearances. The pair of worm gears typically extend outwardly on either side of the cutting head, thereby increasing the overall lateral dimensions of the cutting tool. It is also known to provide the power cutting heads with an automatic feed mechanism which biases the cutting wheel into engagement with the surface of the tube as the cutting head rotates.